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SPN 3216 FMI 20Severity: Warning

SPN 3216 FMI 20: NOx sensor data drift detected – emissions efficiency compromised

Quick Answer

NOx sensor data drift detected – emissions efficiency compromised

Code
SPN 3216 FMI 20
Severity
Warning
Applies to
Check OEM application
Can I drive?
Driving suitability is not established by this code alone.

Common Symptoms

  • Aftertreatment warning light
  • Intermittent derate messages
  • Poor fuel economy

Likely Causes

  • NOx sensor aging
  • Exhaust leaks near sensor
  • Sensor contamination from soot

Common Fixes

  • Inspect exhaust joints for leaks
  • Check sensor mounting and wiring
  • Replace NOx sensor if drift persists
Full technical sections↓

What does SPN 3216 FMI 20 mean?

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NOx sensor data drift detected – emissions efficiency compromised

Detailed guide for SPN 3216 FMI 20

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NOx sensors can slowly drift over time without failing completely.

This causes inaccurate emissions calculations and eventually leads to inducement warnings.

Technician insight

Sensor drift often shows up only after long highway runs or cold starts.

Video walkthrough for SPN 3216 FMI 20

The videos below are embedded using YouTube’s official player. We do not host or claim ownership of this content. Use it as a visual reference and always confirm with diagnostics for your exact truck configuration.

Cascadia DD15 Aftertreatment 1 Intake Nox- Data Drifted High. Spn 3216 Fmi 20
Channel: Quick Dtc • View in BigRigFaults Media • YouTube source
If a creator disables embedding, the video will stop showing here. That’s normal and it’s their right.
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